Demountable blade



Nov. 7, 1939. w. L. VALIQl JETTE 2,178.710

DEMOUNTABLE BLADE Filed May 27, 1935 wi l INVENTOR.

MAL/AM 4. K41. lQUEZ'TE BY ATTORNEYS Patented Nov. 7, 1939 UNITED STATES ATE T OFFICE Harris-Seybold-Potter Company,

Cleveland,

Ohio, a corporation of Delaware Application May 27,

3 Claims.

This invention relates to improvements in demountable blades, particularly blades for the cutters of paper cutting machines. Such machines, in addition to cutting paper, are sometimes employed for cutting fabrics and metal sheets.

Heretofore it has been the universal practice to mount the blade in a rabbet formed in the straight or vertical face of the knife bar, so that the blade stands vertically when the cutting operation is being performed. This necessitates a beveled surface on the blade conforming with the beveled surface on the bar in which the blade is mounted. The bolts or screws by means of which the blade is locked in the knife bar are located necessarily some distance above the cutting edge. When the knife is forced into the work, the reaction of the work against the beveled surface of the blade results in a heavy pressure applieddiagonally upward tending to rock the blade around its fastenings and to loosen the latter, with obviously detrimental effect.

In accordance with the present invention, the blade is located on the beveled side of the knife bar, and the reaction of the work is causedto exert a force which is taken by the body of the knife bar, thereby overcoming the difiiculty above named.

It is one of the objects of the invention, therefore, to provide a mounting for demountable cutter blades in paper cutting machines and the like, which will remain firm and rigid when subjected to severe strains.

Another object is the provision of a demountable blade of thin strip steel wherein the holder for the blade is secured in the same general manner as above described, this thin blade being of low cost and replaceable at an expense commensurate with the cost of sharpening the ordinary blade.

Other objects and features of novelty will appear as I proceed with the description of those embodiments of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawing, in which Fig. 1 is a diagrammatic view showing the knife of a paper cutting machine, constructed in accordance with the present invention, in the position it occupies at the completion of a cut in a stack of paper sheets;

Fig. 2 is a fragmental elevation of a knife bar embodying the invention with a strip steel knif blade in position therein;

Fig. 3 is an end elevation of the same, certai parts being shown in section;

Fig. 4 is a view similar to Fig. 2 showing the 1935, Serial No. 23,580

invention as applied to a removable blade of the type designed to be used and resharpened repeatedly; and

Fig. 5 is an end elevation of the construction shown in Fig. 4, some of the parts being shown in vertical section.

In the drawing, it represents the table of a paper cutting machine. I l is a wood strip mounted in the table to receive the cutting blade as it completes its stroke. A stack of paper sheets is shown at i 2. The knife bar of the machine is indicated at Hi. This bar, it will be observed, has a straight vertical rear surface I l and a forward inclined or beveled surface I5, as is common in the art.

Referring now to Figs. 2 and 3, it will be noted that a rabbet I5 is formed in the beveled or forward side of the knife bar throughout the length thereof. This rabbet is of approximately triangular shape, with the point of the triangle extending downwardly. Within this rabbet is mounted a clamp or holder I! also of substantially triangular cross-section. This clamp is provided at intervals throughout its length with slots l8 for the reception of studs 19 that are threaded into suitably positioned holes in the knife bar l3. Each slot 18 opens into a counterbore 20 on the forward or beveled face of the bar I1, and these counterbores accommodate nuts 2| which are threaded onto the studs I9, and by means of which the clamp or holder is locked in the desired position of adjustment.

The clamp is adjusted the desired distance away from the upper end of the rabbet by means of headed adjusting screws 22 which are mounted in threaded sockets in the clamp. Preferably, the heads of these screws project into depressions 23 formed in the upper end of the clamp l1. By loosening the nuts 2| and backing off the screws 22 more or less, the clamp I! may be caused to descend with respect to the body of the knife bar.

The blade of the knife in this instance is a relatively thin strip steel blade 24 which is set into a rabbet 25 formed in the rear or inner face of the clamp ll, this rabbet being preferably of a depth a trifle less than the thickness of the blade 24 so that, when the nuts 2| are drawn up, the

inclined surface of the clamp I1, and so that the beveled surfaces of the blade when mounted conform exactly with the corresponding surfaces of the bar and clamp.

The blades 24, being made of comparatively thin strip steel, may be produced at relatively low cost, and given a keen accurate edge at the factory, which will be superior to the edge ordinarily obtained by resharpening with the limited equipment and skill usually available for that purpose in the establishments where such work is done. The cost of these blades is commensurate with the cost of resharpening the conventional blades, so that it is economical to purchase a supply of them and discard each blade when it becomes dull.

Referring now to the form of the invention disclosed in Figs. 4 and 5, I show a knife bar 53 with straight and beveled surfaces 14 and 85, as in the first described form of the invention. Here, however, I utilize a blade 26 which is of substantially the same thickness and rigidity as blades now in common use in paper cutting machines. It is, however, mounted on the inclined side of the knife bar instead of upon the straight vertical side, as in conventional practice, and its bevel 2'! is on the rear instead of on the forward side of the knife.

In the forward or beveled side of the knife bar, I form a rabbet 28 the inner wall of which is parallel with the surface i5. At intervals throughout the length of the blade, it is provided with slots 29 for the reception of screws 3%? that are threaded into tapped holes in the body of the knife bar 83. Ihe forward portion of each of these slots is enlarged somewhat to provide shoulders 3| against which the head of the screw 3i engages. Adjustment of the blade downwardly is accomplished by any suitable means, as by headed screws 32 similar to the screws 22 previously described. In this instance, the recess 33 is formed in the knife bar l3 instead of in the blade.

It will be observed that in the case of either one of the two forms of the invention above described, any force exerted upon the knife blade by that portion of the stack of paper which is removed by the out, such portion being indicated in Fig. l by the reference character 35, will tend to push the blade into closer engagement with the body of the knife bar rather than away from such engagement. This force exerted by the work is in the direction of the arrow A, Fig. 1, that is in a direction normal to the beveled surface I5. If the blade were mounted on the rear of the knife bar M, as has been the former practice, obviously this force would tend to spring the blade away from the bar.

Having thus described by invention, I claim:

1. In a cutter for paper cutting machines, a Vertically movable knife bar having one beveled surface and one vertical surface, said bar having a rabbet in its lower edge opening toward the beveled surface of the bar, a strip steel cutter blade in said rabbet bearing against the inner wall thereof, a clamp mounted in said rabbet engagingthe major portion of said blade, and means for adjusting the clamp to advance the cutting edge of the blade, said clamp having thrust absorbing means acting Without regard to clamp and blade adjustment to withstand cutting pressure applied along the plane of the blade.

2. In a cutter for paper cutting machines, a vertically movable knife bar having one beveled surface and one vertical surface, said bar having a rabbet in its lower edge opening toward the beveled surface of the bar, the inner wall of the rabbet being inclined, a strip steel cutter blade in said rabbet bearing against the said inner wall thereof, a clamp mounted in said rabbet engaging the major portion of said blade and having a shoulder against which the rear edge of the blade bears at all times, adjustable means for resisting movement of the clamp away from the lower edge of the knife bar, and means acting transversely of the clamp for securing it to the knife bar.

3. In a cutter for paper cutting machines, a vertically movable knife bar having one beveled surface and one vertical surface, said bar having a rabbet in its lower edge opening toward the beveled surface of the bar, a strip steel cutter blade in said rabbet bearing against the inner wall thereof, a clamp mounted in said rabbet engaging the major portion of said blade and having a shoulder against which the rear edge of the blade bears, means for adjusting the clamp in said rabbet toward and away from the lower end of the knife bar, said adjusting means being capable of withstanding cutting pressure acting in the plane of the blade, and means for locking the clamp in a given position of adjustment.

WILLIAM L. VALIQUETTE. 

